1. Field of the Invention
This invention relates generally to exercise equipment and more particularly to a multipurpose self spotting weight lifting apparatus.
2. Prior Art and Information Disclosure Statement
Exercise equipment generally falls into one of two main categories. A first category of exercise equipment is primarily concerned with improving the cardiovascular system by performing rapid repetitious movements to induce deep breathing and rapid pulse rate. Exercise equipment of the second category is more concerned with improving muscle tone and increasing muscle mass. Weight training generally belongs to the second category.
The most common apparatus for weight training are free weights (barbell) and weight lifting stations. Free weights usually include a long steel bar provided with a number of disk shaped weights and collars for positioning the weights on the bar. Free weights are often used with a weightlifting bench.
One common danger of lifting free weights is that a weight lifter might injure himself by losing control and dropping the weights. It is therefore a common safety practice for weight lifters to exercise in pairs so that one lifter can act as a "spotter" for the other lifter. A spotter stands behind the lifter and grabs the barbell if the lifter seems to be losing control of it. This method is often inconvenient since a lifter may not find a partner.
U.S. Pat. No. 4,564,194 to Dawson is an apparatus intended to overcome this problem and is hereby incorporated by reference into this specification. The invention comprises a weight lifting station having a compound bar including a central bar within a sleeve centrally positioned on the central bar. Disk weights are positioned on each end of the bar. Two sliders are attached to the bar, one on each end of the bar, which are slidably mounted on vertically oriented guide posts. Each vertical post has a vertical row of locating holes. The sleeve centrally located on the center bar extends almost to each vertical post. Two "L"shaped stops are attached to the sleeve, one at each end of the sleeve so that when the sleeve is rotated by a turn of the users wrist, each stop is brought into engagment with one of the locating holes in the guide posts. The stops thereby provide a weight lifter with a method of self spotting. An additional pair of independent stop pins are also attachable to the posts for supporting the bar at any lower position for starring the exercise. Therefore, the user can perform his exercise by starting the lift from the lowermost position which is where the independent stop pins are located, then secure the bar at any intermediate height by simply fuming his wrist to rotate the spotter stops into adjacent apertures.
A problem with the Dawson aparatus as disclosed is that since the safety stop pins are completely separable from their respective vertical posts, they can be disengaged from the uprights during the exercise leading to great distress to the user. Another problem with the separable stop pins as disclosed is that one or both of the pins may be lost so that a user may be tempted to use the apparatus without using the independent stop pins. Yet another problem with the independent stop pins as disclosed is that these stop pins must absorb great impact on those occasions when the user collapses under the exhaustive effort of performing an exercise so that the bar comes crashing down on the stop pins. This ultimately leads to distortion of the posts and stops and unreliable attachment of the stops to the posts as well as slicking of the guides on the uprights.
Another problem with the Dawson apparatus is that excessive rotation of the wrists such as when performing bench presses in order to disengage the stops misaligns the forearm with the direction of application of force thereby detracting from the ability of the user to exert his maximum effort.
The Dawson invention further discloses a cable attached at one end to a pulldown bar and extending over an overhead fixture of pulleys and down to a hook which may be detachably engaged with the center of the compound bar. The user pulls down on the pulldown bar thereby lifting the compound bar with weights in order to perform the exercise. The problem with this arrangement is that during the course of the exercise, the stop pins can swivel into engagement with the posts thereby inadvertently locking the compound bar while the user is trying to perform his exercise with the pulldown.
Another problem with the Dawson invention as disclosed is that considerable frictional force is developed between the metal sleeves sliding on the metal upright posts resulting in unpredictablity of the force required to perform the exercise.